Process for the distillation of oil containing salts of hydrochloric acid



1942. J. H. MccLlNTocK 2,306,484

PROCESS FOR THE DISTILLATION OF- OIL CONTAINING SALTS OF HYDROCHLORIC ACID Dec. 29,

Filed Feb. 23', 1940 QN NN III 4 "uga Y It is'known in L111'@.Selmef` l .c A suldes' which 'are characterized by the-fact that Patented Dec. 29, 1942 asoaieij vAcmr JohnH. McClintockfCranford, NQJ'.;assi-giuri'.to".4v I,

" Standard Oil DevelopmentCompany, a corporation of Delaware lApplication February 23, 19,40;

(Cl. Y. stable l nder the temperature and pressure condi- A3 Claims.

The present invention relates to the refiningv of mineral oils... The invention is moreparticularly concerned with a method forthe prevention of corrosion of the refining equipment. In accordance with Vthe present process, petroleum oils which tend'to cause excessive corrosionare distilled in the presence of a reagent 'whichserves to substantially' completely'v eliminate prohibitive corrosion'of the equipment. A special modification of the inventionis directed to an improvedV process for the productionof hydrogen sulfidefree 'petroleum oilsboiling in themotor fuel boiling range'l 'from' petroleum crude oils containing acid-formingl constituents, In accordance -with .thev present fpjrocess, petroleum oils containing vacid-forming constituents are distilled in the presence of a sulfide `selected fromv the classof suliides which are characterized by' the fact that they form stable salts whichdo .noty decompose under distillation conditions into'harmful acidic substances',

theY art thatyarious petroleum crude oils contain appreciable l'amounts of,v constituents which, upon distillation of the oil, form corrosive acids which materially decrease the f life of the distillation and'related equipment, re- ,sulting in a substantial increase in operating costs. Particularly harmful acidic-forming 'constituents v`contained! inv unreflned petroleum oils arexrelatively unstable salts ofhydrochloric acid,

`as for example, magnesium, `calcium and iron chloride which hydroliz'ejtoj jform free hydrochloric acid. Thus'numeroussuggestions have been made that various reagents be addedfto petroleum oils prior 'toi distilling the same in A order tosprevent the formation ofr or to neutralize freeacidswhich may be formed. lSubstanceswhich have been employed for this purposeara'for example, aqueous solutions of sodium, hydroxide and sodium'carbonate. These materials due'in Iv'have now discovered a process by which it is troleum oils containing acid-forming constituents utilizing a reagent whichwill substantially entirely prevent corrosionof ther equipment and which will not fuse with the metallic surfaces of the same. lMyprocess comprises distillingrmineral oilswhich'tend 'to cause `excessive corrosion of the distillation andi related equipmentY in the 'a sulfide-selected from the class of they form salts which are entirely substantially,

part to their cost are not entirely satisfactoryggoV "erncelf'to' the attachedtions v.prevailing in 'the distillation operation.

Subst'aifees'V of this type areyfor example, am-

nonium'fs'ulde, sodium sulfide and potassium sulfide., Ap'referred'modification of my inven- Ain'g'"nsulfurcompounds vand `acidic forming materialsV asfo'r example, relatively unstable salts of hydrochloricjacid suchy tas magesium chloride, calciumchloride and iron chloride., In accordlnce with'my preferred adaptation of the invention, -these` unrened crude'oils -are distilled in the-:presence of-sodium; suliide solutions vwhich argl-secured; iri the removal of hydrogen sulde irorrrthe lower boiling constituents of said crude oilsbyftreating said lower-boiling constituents 'with a sodium hydroxide solution. 4The lower lboiling constituents preferably boil inthe motor My lrecess maybe readilyv understood by refdrawing illustrating 'modifications of the samer-#For 'purposes of description itjis assumed-:that the feed oil is an un- Vrefined petroleum roil containing appreciable quantitiesr of acidic forming substances such as magnesiumiand calcium chloride. [The feed oil is introduced into 'distillation tower l by means of 'feedf line 2-.n Prior to introducingthefeed oil "intodistillationtower l it is mixed with asuliide 'jsolutionwwhich is introducedintodfeed line y2 by irieagns'ofqline. For purposes of description it isassumed'the sulfide solution is an aqueous sodium sulfide solution. Efficient mixing of the feed eiland-reagent is secured by -meansofmixer `4.- ,-V'Iemperature and` pressure conditions are A -maintained inr distillation tower I, adapted to revove overhead by means ofv line Blower boiling ydrocarbon fractions preferably boiling inthe otorfuel boiling range. Under certain condiitfmay berdesirable to withdrawV as a side y 45fhfsr'trjream bymeansl'of line`6 a; relatively high boiling l fraction of hydrocarbons boiling substantially in possible to efficiently*andeconomically distill -pethe'y motor fuel boiling lrange.A If this*V operation be employed the boiling k,range of -this stream will be, from abouty 250 to 4202 Intermediate and higher boilingrangeY streams, `as for example Vgas il'fractifons and jreduce'd crude fractions are withdrawal by-means of lines 1 and 8 respectively.

oil and reduced crude streams may be -handled in any manner desirable. Generally 'theyare processed by various cracking operations Afor the production of cracked motor fuels, heaty ingoils andthe like. 'I 'he cracked products are v.then refined vbyvarious lrefining operations such ooi as `debutanization. stabilization, acid treating yand the ylikein.. order to produce finished products. 'I'he distillate fraction removed overhead from distillation tower I by means of line 5 is condensed in condenser 9 and passed to distillate drum IIJ. moved from distillate drum I by means of line II and handled in any desired manner. These gases may be processed for the recovery of valuable hydrocarbons which may be included in motor fuels or may be passed to a burning line. The condensed distillate containing various sulfur compounds, as for example hydrogen sulfide, is removed from distillate drum Ill by means of line I2, and passed through treating plant I3, in which it is contacted with an alkaline solution preferably a solution of sodium hydroxide. Treating plant I3 may comprise any number of stages arranged in any desirable manner. The sodium hydroxide solution is introduced into treating plant I3 by means of line I4. The mixture is withdrawn from treating plant I3 by means of line I5 and passed to settling unit I6, in which the spent sodium hydroxide solution comprising a sodium sulfide solution substantially free of sodium hydroxide separates from theV treated oil. Hydrogen sulfide-free oil is withdrawn from settling unit I6 by means of line I'I and passed into storage tank I8. The oil is withdrawn from storage tank I8 by means of line I9 and handled in any manner desirable. erally the oil is sweetened and blended into a finished refined product. If the operation be conducted under conditions to remove a relatively higher boiling fraction of hydrocarbons boiling in the motor fuel boiling range by means of line 6 this fraction is cooled in cooler 1 and passed to treating plant 20, which may comprise any suitable number of units arranged in any desirable manner.. This oil in treating plant 20 is thoroughly contacted with an alkaline solution preferably with a sodium hydroxide solution which is introduced by means of line 2|. The mixture is withdrawn from treating unit 20 by means of line 22 and passed to settling drum 23 from which a hydrogen sulfide-free oil is Withdrawn by means of line 24 and passed to storage tank 25. The oil withdrawn from tank 25 by means of line 26 may be acid treated or reformed or further processed in any manner desired. The spent sodium hydroxide solution comprising sodium sulfide and substantially free of sodium hydroxide is Withdrawn from settling drums I6 and 23 by means of lines 21 and 28 respectively. These solutions are passed into sodium sulfide storage 29 by means of line 3D from which it is withdrawn by means of line 3 and introduced into the unrened feed oil. Excess solution may be withdrawn from storage tank 29 by means of line 3| and disposed of as desired. Under certain conditions it may be desirable to utilize or to employ in part, a sodium sulfide not produced in the manner described in which casefthe solution is introduced into the feed oil by means of line 32.

The present invention may be widely varied. The process may be applied to any distillation operation utilized in the refining of mineral oils containing sulfur and acid forming compounds. The process, however, is particularly adapt-ed for the production of hydrogen sulfide-free refined oil produces boiling in the motor fuel boiling range from sulfur-containing crude oils which also contain acid-forming salts, such as magnesium chloride and calcium chloride. Although any sulfide which has the abilityto prevent the formation vof or to neutralize the free acids Uncondensed and fixed gases are reformed may be used. I have found that the preferred sulfides are the alkali metal sulfides particularly sodium sulfide.

The amount of the sulfide added to the un- Arened oil will be a function to a large extent of the characteristic of the unrefined oil and of the particular sulfide employed. The quantity added should be at least suflicient to completely neutralize the acid-forming constituents present. vIn general, it is preferred that the quantity added should be several times the amount equivalent to secure theoretical complete neutralization. The concentration of the sulde solutions may also vary considerably depending upon the various factors. For example, when employing spent sodium hydroxide solution the concentrations will vary depending upon the relative proportions of sodium sulfide 'and sodium hydrogen sulfide present. We have found, for example, that sodium sulfide solutions comprising from 0.01 1b. to 0.1 lb. of sodium sulfide and from 0.1 to 0.5 lb. of sodium hydrogen sulfide er gallon are very satisfactory. When employing the preferredv modication of the invention in order to secure the desired concentration of sodium sulfide and sodium vhydrogen sulfide and to substantially completely eliminate freesodium hydroxide, the spent sodium hydroxide solution may be processed or concentrated prior to introducing the same into the oil feed. The spent sodium hydroxide solution should comprise sodium sulfide and sodium acid sulfide and should preferably be substantially completelyV free of sodium hydroxide.

In order to further illustrate the invention, the following examples are given which should not be construed as limiting the invention in any manner whatsoever.

Example 1 Operations were conducted on West Texas crude oils and the quantities of hydrochloric acid evolved per unit quantity of oil determined. In one operationvno'sulde was added to the oil. In a second operation a spent sodium hydroxide solution free Vof sodium hydroxideV and secured from a plant operated for the removal of hydrogen sulfide from petroleum, hydrocarbons boiling in the motor fuel boiling range was employed. In a third operation sodium sulfide was utilized. The amounts of the solutions utilized were controlled to theoretically neutralize of the acidity. The quantities of acidicvapors evolved in the respective operations were Vas follows:v V-

sulfides were particularly leffective and that by utilizingvasomewhat greater quantity than the theoretical amount needed, substantially complete removal of the acidic `constituents will Vbe effected.

Example 2 n a commercial distillation operation when processing East Texas crude oil a visual inspection disclosed that considerable corrosion of the distillation equipment occurred. This corrosion was substantially completely prevented by employing a spent sodium hydroxide solution which Was essentially free of sodium hydroxide and comprised about 0.1 lb. of sodium sulflde and about 0.1 lb. of sodium hydrogen sulde per gallon.

What I claim as new and Wish to protect by Letters Patent is: n

1. Process for the distillation lof petroleum oils containing salts of hydrochloric acid of the class consisting of magnesium chloride, calcium chloride and iron chloride comprising distilling said oils in the presence of a spent sodium hydroxide solution secured in the removal of hydrogen sulfide from petroleum oils said spent sodium hydroxide solution being substantially completely free of sodium hydroxide.

2. Process for the production of a hydrogen sulfide free rened petroleum oil boiling substantially in the motor `fuel boiling range from an unrened petroleum oil containing sulfur compounds and salts of hydrochloric acid selected from the class consisting of magnesium chloride, calcium chloride and iron chloride comprising distilling said unrened petroleum oil in the presencerof a spent alkali metal hydroxide solution secured in the removal of hydrogen sulde from said refined petroleum oil derived from said unrened petroleum oil, said spent alkali metal hydroxide solution being substantially completely free of alkali metal hydroxide constituents.

3. A process for the distillation of oil containing salts of hydrochloric acid of the class consisting of magnesium chloride, calcium chloride and iron chloride, comprising distilling said oil in the presence of an added solution containing a sulfide salt selected from the class consisting of sodium sulfide and potassium sulfide.

JOHN H. MCCLINTOCK. 

